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(Sub)millimeter-Wave Antennas
Pítra, Kamil ; Křesálek,, Vojtěch (referee) ; Küppers, Franko (referee) ; Raida, Zbyněk (advisor)
Disertační práce se zabývá návrhem a optimalizací kruhově polarizované anténa pro oblast terahertzových kmitočtů. V práci se věnuji zjednodušené teorii terahertzového zdroje a návrhu vhodné antény pro tento zdroj. Návrh je zaměřen na dosažení kruhové polarizace z lineárně polarizovaných antén. Abych potlačil šíření povrchové vlny na elektricky tlustém dielektrickém substrátu, věnuji se návrhu a optimalizaci specifických periodických struktur. Návrh těchto struktur je poměrně komplikovaný, protože neexistuje přímočarý vztah mezi vlastnostmi struktur s elektromagnetickým zádržným pásmem (EBG) a geometrií buňky. Abych vhodně koncentroval vyzařovanou energii do úzkého svazku, věnuji se návrhu a optimalizaci částečně odrazného plochy (PRS), které působí jako planární čočka pro terahertzovou anténu.
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Woven antennas
Fikar, Jan ; Pítra, Kamil (referee) ; Raida, Zbyněk (advisor)
The thesis is aimed to design textile antennas that can operate in the ISM band 5.8 GHz. Attention is turned to practical exploitation of these antennas under regular conditions. Variations of the bandwidth of the antenna due to washing and waterproofing will be observed. Finally, the impact of the proximity of living tissue on the parameters of antennas will be studied.
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Planar parabolic reflector antenna
Procházka, Petr ; Pítra, Kamil (referee) ; Mikulášek, Tomáš (advisor)
This master's thesis deals with a design of a planar parabolic reflector antenna. The thesis is divided into several parts. The first section is dedicated to the theory of the parabolic antenna design and a basic introduction of the SIW technology which is used for the realization of an antenna prototype. The second chapter deals with the design of individual parts of the antenna (i. e. a primary and secondary reflector and an antenna feeder excited by a waveguide) for particular assignment. The third part is focused on modeling the designed antenna using ANSYS HFSS. Other parts of the thesis include a conversion of the proposed antenna to the SIW technology and a design of a transition between the antenna and a feeding waveguide WR15. The last part of the thesis deals with measuring of the reflection coefficient and the radiation pattern of the fabricated antenna prototype.
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Patch antenna with EBG substrate
Cepek, Tomáš ; Pítra, Kamil (referee) ; Hebelka, Vladimír (advisor)
The aim of the thesis is to describe EBG substrate and exminate his influence on some types of antennas and choose one of them for realization. In first part this thesis describes the paramaeters of antenna in generall, in the second part is dedicated to introduction with EBG substrate mainly on the surface with the high impedance (HIES). The third part deals with the simulations of microstrip patch antennas with EBG substrate and without EBG substrate. In the last parts was designed and optimized antenna using superstrate.
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Antennas with metamaterial radomes
Martínek, Luděk ; Tkadlec, Roman (referee) ; Pítra, Kamil (advisor)
This thesis deals with microstrip antennas covered by the metamaterials. First, are described planar antennas, their problems and the emergence of surface waves. Surface waves can cause unwanted coupling among particular parts of the structure and can degrade its parameters. The problem can be solved using an electromagnetic band gap structure (EBG). These periodic structures are able to suppress surface waves in different frequency bands. It is shown how the EBG structure in the function superstate improve directivity and antenna gain. Radiation conventional microstrip antenna with metallo-dielectric EBG superstrate and with the purely dielectric double-layer superstrate is described. The both structures are designed and simulated in CST Microwave Studio program. Further is described the antenna radiation with so-called mushroom structure and metallo-dielectric EBG superstate. The structure is again designed and simulated in CST MWS program. Finally, there are two structures with metallo-dielectric superstate implemented and measured.
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Dual-Band Helix Antenna for WiFi band
Šrajbr, Michal ; Tkadlec, Roman (referee) ; Pítra, Kamil (advisor)
This master’s thesis is focused on the properties and types of helical antennas. The helical antenna work in the different modes. These modes are described in this thesis. There are also discussed possibility for design a dual-band helical antennas. The main aim of this work is the selection of a suitable solution and design a dual-band helical antenna for the WiFi band working at resonance frequencies of 2,4 GHz and 5 GHz. The simulation of this antenna was performed in the program CST Microwave studio.
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Wideband Sinuous Antenna with Dual Polarization
Haloda, Jiří ; Tkadlec, Roman (referee) ; Pítra, Kamil (advisor)
This paper deals with sinuous broadband antenna, witch operating frequency 1 to 6 GHz. The antenna parameters, which change their physical dimension were shown in this paper. Antenna structure is planar and feeding network line have to be planar too. There are different ways to describe and construct from unbalanced to balanced line by baluns. There are also design impedance transform to match antenna in this paper. The simulation and measured results are showen the antenna has wideband character.
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Antennas for milimeter-wave bands
Pítra, Kamil ; Svoboda, Petr (referee) ; Raida, Zbyněk (advisor)
This thesis describes design and experimental verification of three types of the wideband antenna Bow-tie antenna, Vivaldi antenna and Spiral antenna. The tracked parameters are bandwidth, input impedance, gain and directivity patterns. Next step is design of millimeter-wave horn antennas. Attention is turned to the proper construction of a wideband feeder of the horn. For the final antenna structure, a bow-tie dipole and a Vivaldi antenna were chosen. The antenna construction is aimed to provide a wide bandwidth on one hand and a high gain on the other hand.
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Low Altitude FM Radioaltimeter
Pítra, Kamil ; Šebesta, Jiří (referee) ; Józsa, Ladislav (advisor)
The aim of my bachelor thesis is to design a Low altitude FM radioaltimeter based on heterodyne frequency measurement. Radiolocator works in 5,760 GHz frequency band. Its design is based on solving peripheral circuits. There are no RF modules used. Design of each of them is supported by simulations and measurements.
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